Arrangement for controlling the flow out of a tundish

Abstract

In continuous casting of steel, the flow out of the tap hole ( 11 ) in the tundish ( 10 ) is controlled by a stopper rod that is rotatable so as to give the molten steel a swirling motion. This rotation reduces the risk of deposits in the tap hole and in the discharge tube ( 12 ). A non-rotatable sleeve around the stopper rod ( 16 ) extends through the slag layer ( 18 ) and into the molten steel ( 17 ). Protective gas is supplied to the gap between the stopper rod ( 16 ) and the sleeve ( 30 ) to prevent air from being drawn through the gap and into the molten steel.

The invention claimed is: 
     
       1. An arrangement for controlling flow of a tundish ( 10 ) that has a tap hole ( 11 ) for molten metal, said arrangement comprising an axially movable stopper rod ( 16 ) for controlling the flow out of the tap hole and a device ( 21 ,  22 ) for rotating the stopper rod;
 a sleeve ( 30 ) non-rotatably mounted around the stopper rod ( 16 ) by a mounting element attached to said sleeve; wherein said sleeve is arranged to extend through a slag layer ( 24 ) and down into molten metal ( 17 ); and means ( 31 ) provided for supplying protective gas to an annular gap between the stopper rod ( 16 ) and the sleeve ( 30 ) for preventing air from being drawn into the annular gap. 
 
     
     
       2. The arrangement as claimed in  claim 1 , wherein said arrangement is provided for continuous casting of steel.